There are a number of product applications for high volume, low cost color scanners using three linear sensors, one each for red, green, and blue, on a single chip. One such system is disclosed in U.S. Pat. No. 4,278,995, entitled "Color Line Sensor for Use in Film Scanning Apparatus" by W. T. Fearnside et al, which patent is assigned to Eastman Kodak Company, the assignee of the present application. These types of scanners require expensive "apochromatic" lenses which are designed to yield red, blue, and green images which are exactly the same size and which are focused at the same plane so that the identically sized CCD linear sensors, one for each color red, green, and blue, capture a properly registered image when positioned at the focal plane of such a lens.
One way to reduce the cost of this type of scanner is to use an "achromatic" lens and some means for correcting the distortions normally encountered with the use of such a lens. For more details about "apochromatic" and "achromatic" lenses see: Ray, Sidney F., entitled "Applied Photographic Optics: Imaging Systems for Photography, Film and Video", Focal Press, Boston, Mass. 1988, ISBN 0-240-51226-X.
Another patent of interest for its teachings of an approach for correcting distortions caused by lenses is U.S. Pat. No. 4,467,361, entitled "Image Pick-Up Apparatus" by K. Ohno et al, wherein an image sensor is curved into a spherical shape to correspond to the curvature of field of an objective lens. This curvature may take any desired shape to correct for various aberrations of the objective lens.